Abstract
The development of efficient perovskite light-emitting diodes(PeLEDs)relies strongly on the fabrication of per-ovskite films with rationally designed structures(grain size,composition,surface,etc.).Therefore,an understand-ing of structure-performance relationships is of vital importance for developing high-performance perovskite de-vices,particularly for devices with in-situ fabricated perovskite nanocrystal films.In this study,we reveal the vertical structure of an in-situ fabricated quasi-two-dimensional perovskite film.By combining time-of-flight sec-ondary ion mass spectrometry,energy dispersive spectroscopy,grazing incidence wide-angle X-ray scattering(GIWAXS),and low-temperature photoluminescence spectra,we illustrate that the resulting in-situ fabricated DPPA2Csn-1Pbn(Br0.3I0.7)3n+1(DPPA+:3,3-diphenylpropylammonium)film has a gradient structure with a very thin layer of ligands on the surface,predominantly small-n domains at the top,and predominantly large-n do-mains at the bottom owing to the solubility difference of the precursors.In addition,GIWAXS measurements show that the domain of n=2 on the top layer has an ordered in-plane alignment.Based on the understanding of the film structure,we developed an in-situ fabrication process with ligand exchange to achieve efficient pure red PeLEDs at 638 nm with an average external quantum efficiency(EQE)of 7.4％.The optimized device had a maximum luminance of 623 cd/m2 with a peak EQE of 9.7％.
基金项目
accelerator scientists and the staff of beam-lines at SSRF(BL17B1)
accelerator scientists and the staff of beam-lines at SSRF(BL16B1)
accelerator scientists and the staff of beam-lines at SSRF(BL14B1)
accelerator scientists and the staff of beam-lines at SSRF(BL13W)
accelerator scientists and the staff of beam-lines at SSRF(BL11B)
accelerator scientists and the staff of beam-lines at SSRF(BL01B1)
国家自然科学基金(61735004)
NETL
NSTL
万方数据